http://comum.rcaap.pt/handle/123456789/863 2013-05-16T23:08:56Z http://comum.rcaap.pt/handle/123456789/1297 Title: Transesterification of rapeseed oil with methanol in the presence of various co-solvents Authors: Pardal, Ana Cristina; Encinar, J.M.; González, J.F.; Martínez, G. Abstract: In this study, transesterification of rapeseed oil using various co-solvents(diethyl ether (DEE), dibutyl ether (diBE), tert-butyl methyl ether (tBME), diisopropyl ether (diIPE), tetrahydrofuran (THF), and acetone) was studied. The variables affecting the ester yield during transesterification reaction, such as catalyst content, methanol:oil molar ratio, methanol:cosolvent molar ratio, co-solvent type, catalysts type, agitation rate and reaction temperature were investigated. The process was monitored by gas chromatography, determining the concentration of the methyl esters. Biodiesel was characterized according to ISO norms. Among the studied co-solvents, the DEE and tBME take to the best results, however diIPE, diBE and acetone hardly improve the obtained results using only methanol. Within the range of studied variability, the rest of variables do not exercise a very significant influence. The best results are obtained with 0.7 % of KOH, a molar ratio methanol/oil of 9:1, a molar ratio co-solvent/methanol 1:1, an agitation rate of 700 rpm and a temperature of 30 ºC Description: Comunicação apresentada no «Third International Symposium on Energy from Biomass and Waste», Venice(Italy), Novembro 2010 2010-11-01T00:00:00Z http://comum.rcaap.pt/handle/123456789/1296 Title: Transesterification of vegetables oil in subcritical methanol conditions Authors: Pardal, Ana Cristina; M. Encinar, J.; F. González, J.; Martínez, G. Abstract: In this study, transesterification of rapeseed oil using subcritical methanol and potassium hydroxide as catalyst was studied. The variables affecting the methyl ester yield during the transesterification reaction, such as the catalyst content, reaction temperature, reaction time and the molar ratio of alcohol to oil, were investigated. The results are compared to the obtained using co­solvents. The evolution of the process was followed by gas chromatography, determining the concentration of the methyl esters. The biodiesel was characterized by its density, viscosity, saponification value, iodine value, acidity index and water content, according to ISO norms. High methyl ester yield and fast reaction rate could be obtained even if the reaction pressure was relatively low, which is quite favourable to the production of biodiesel in industry. Description: Comunicação apresentada na 18th European Biomass Conference and Exhibition, Lyon (França), Maio de 2010 2010-05-01T00:00:00Z